Updating software

ABSTRACT

This invention relates to a method and apparatus for updating software. In particular this invention relates to a method, system and computer program for updating an operating system in a hypervisor comprising: determining a new version of a component of the operating system; installing the new component version; 
     measuring an identifying characteristic of the component and making it available to an attestation system; notifying the attestation system that a component has been updated to a new version whereby, when the attestation system finds that the identifying characteristic of the new component does not match a pre-stored attestation value it is aware that a legitimate mis-match could have occurred. The installing of the new version of the component comprises: identifying an updater associated with new version of the component; measuring an identifying characteristic of the identified updater; loading and installing the new version of the component; and making both the identifying measurement of the updater and the new version of the component available to the attestation system.

TECHNICAL FIELD

This invention relates to a method and apparatus for updating software.In particular this invention relates to trusted boot and remoteattestation processes. Trusted computing, trusted boot, and remoteattestation, as described in this specification, generally relate totechnology standards developed by a standards group called the TrustedComputing Group.

BACKGROUND

Trusted boot is a procedure for booting and establishing a chain oftrust in a trusted computing system. Components of the boot can becryptographically measured and stored in a secure device, for example aTrusted Platform Module (TPM). Each boot component measures and storesin the secure device a characteristic measurement of the next bootcomponent, this measurement is taken before control is transferred tothe measured component. Once the system is running, the measurements canbe extracted for inspection by a remote system using a remoteattestation process, for example by Direct Anonymous Attestation (DAA).A sequence of measurements is described as a chain of trust.

Computer systems are frequently updated with new features and softwarefixes. An update may need to change a boot component which forms part ofthe chain of trust and after such an update remote attestation will showa change of measurement; the chain of trust will be broken. With manysystems and many updates this scales into a larger difficult managementproblem. The change of measurement will only “show” after at a minimum are-measure. The re-measure may only occur at reboot, or occur atrun-time (depending on how the system is built).

Therefore, there is a need in the art to address the aforementionedproblem.

SUMMARY OF INVENTION

In a first aspect of the invention there is provided a method forupdating code in an executing environment comprising: installing newcode; measuring an identifying characteristic of the new code and makingthe identifying characteristic available to an attestation system;notifying the attestation system that code has been updated to a newversion whereby, when the attestation system finds that the identifyingcharacteristic of the new code does not match a pre-stored attestationvalue it is aware that a legitimate mis-match could have occurred.

In the preferred embodiment, code is a component used in the bootprocess but it could also refer to another component in thechain-of-trust that is not booted. In other embodiments, code a whole orpart of firmware, a hypervisor, a virtual machine, an operating system,or application. New code can be a new version of a component or acompletely new component.

A pre-stored attestation value is a reference used by the attestationsystem to test for a valid identifying characteristic of a systemcomponent. The pre-stored attestation value is saved in the attestationsystem by system administration or acquired by some initializing processwhereby an initial identifying characteristic of a component is trustedand used by the attestation system as the attestation value.

Advantageously the method further comprises determining the existence ofa new version of an operating system component whereby the updatingstage is performed automatically.

The invention notifies the attestation system of the update butattestation values can only be updated by the attestation system or by asystem administrator. Only in a less secure embodiment could attestationvalues be updated by the hypervisor. In the preferred embodiment thehypervisor has no access to the attestation system except bynotifications; the attestation system must perform an attestationdirectly after the notification whereby it checks the origin of the newversion of the component. Once it has verified the origin of the newcomponent it can, after a future reboot, accept the boot measurement ofthe new component even if it does not match the stored attestationvalue.

A hypervisor notification stage is added to the known software updateprocess so that the chain of trust starts with the hypervisor. In thepreferred embodiment the notification stage consists of the updatedsystem notifying the attesting system with a “test me” message so thatthe attestation system is aware that a new measurement has been made.The attestation notification stops the attesting system from panickingwhen the attested system reboots and encounters different measurements.

The preferred embodiment allows a trusted component such as thehypervisor to participate in the measuring process and measure anothercomponent so that the attesting system can trust the measured component.

Advantageously, the installing of the new version (651.N) of thecomponent (616.N) comprises: identifying an updater (612.N) associatedwith new version (651.N) of the component; measuring an identifyingcharacteristic of the identified updater (612.N); installing the newversion (651.N) of the component; and making the identifying measurement(PCR17) of the updater available to the attestation system (620) wherebythe attestation system (620) can match the identifying measurement(PCR17) of the updater (612.N) to a pre-stored attestation value (624.N)to validate a legitimate update. For clarity and for example only,reference numbers from FIG. 6 have been added to the above paragraph.

More advantageously, the attestation system, directly after thenotification, checks the origin of the new version of the component thatit finds in the hypervisor. In the preferred embodiment checking theorigin of a component includes checking the component that installed theupdate but in other embodiments other checks may be made such as wherethe update came from or how it was installed. Furthermore if themeasurement does not match an attestation value and the attesting systemhas checked the origin of the corresponding component then performingone or more of: updating the attestation value with measurement of thenew version of the component; and/or notifying an administration levelthat a measurement does not match an attestation value and whether theattesting system recognises the origin of the component.

In a second aspect of the invention there is provided a method forupdating and attesting an operating system component in a hypervisorcomprising: determining a new version of a component of a operatingsystem; installing the new component version;

measuring an identifying characteristic of the component and making itavailable to an attestation system; notifying the attestation systemthat a component has been updated to a new version whereby; and wherebywhen the attestation system finds that the identifying characteristic ofthe new component does not match a pre-stored attestation value it isaware that a legitimate mis-match could have occurred.

In a third aspect of the invention there is provided a method of testingthe integrity of a program comprising:

extracting a component measurement stored by the program installationprocess; testing the component measurement with reference measurementsstored by the testing system and failing the measurement if it does notmatch; further testing the failed component measurement and failing itagain if it does not originate from another component known to thetesting system; and indicating a pass if the component measurementpasses one test and a fail if the measurement does not pass either ofthe tests.

A fourth aspect of the invention is provided as described in claim 11.

A fifth aspect of the invention is provided as described in claim 19.

A sixth aspect of the invention is provided as described in claim 20.

Viewed from a further aspect, the present invention provides a computerprogram product for updating code in an executing environment, thecomputer program product comprising:

a computer readable storage medium readable by a processing circuit andstoring instructions for execution by the processing circuit forperforming a method for performing the steps of the invention.

Viewed from a further aspect, the present invention provides a computerprogram stored on a computer readable medium and loadable into theinternal memory of a digital computer, comprising software codeportions, when said program is run on a computer, for performing thesteps of the invention.

This specification presents a solution that allows a system to informthe attesting party of what to expect on the next Trusted Boot for avirtualised system using a virtual TPM.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only,with reference to preferred embodiments, as illustrated in the followingfigures:

FIG. 1 is a schematic deployment diagram of a prior art trustedcomputing system, in accordance with the prior art, and in which apreferred embodiment of the present invention may be implemented;

FIG. 2 is a schematic process diagram of the prior art trusted computingsystem, in accordance with the prior art, and in which a preferredembodiment of the present invention may be implemented;

FIG. 3 is a schematic process diagram for attesting the prior arttrusted computing system, in accordance with the prior art, and in whicha preferred embodiment of the present invention may be implemented;

FIG. 4 is a schematic process diagram for updating the prior art trustedcomputing system, in accordance with the prior art, and in which apreferred embodiment of the present invention may be implemented;

FIG. 5 is comparison diagram showing equivalent steps of an embodimentupdate process and the prior art update process, in accordance with theprior art, and in which a preferred embodiment of the present inventionmay be implemented;

FIG. 6 is a schematic deployment diagram of a system, according to apreferred embodiment of the present invention;

FIG. 7 is a schematic process diagram of the update process, accordingto a preferred embodiment of the present invention;

FIG. 8 is a process diagram of new component loading process, accordingto a preferred embodiment of the present invention;

FIG. 9 is a process diagram of attestation process, according to apreferred embodiment of the present invention; and

FIG. 10 is a schematic deployment diagram of a system of a physicalembodiment

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a simplified deployment diagram of a prior art trusted systemcomprising: a platform 10; a Trusted Platform Module 20 (TPM 20) and anattestation system 30. Platform 10 comprises: a boot process 200(described below and with reference to FIG. 2); an update process 12 andboot components 15.1 to 15N (here and elsewhere in this specificationthe letter N is used to represent a number but not any specific number).Boot components 15 include: boot components 15.1 to 15N. TPM 20comprises platform configuration registers 22.1 to 22N. TPM 20 is showndeployed separate from the platform 10 but it could also be part of theplatform 10. A platform configuration register PCR is also referred toas a register. Attestation system 30 comprises an attestation process300 and attestation values 34.1 to 34N. Attestation system 30 is showndeployed separate from the platform.

FIG. 2 is a simplified process diagram of prior art boot process 200comprising a sequence of steps 202 to 212 for executing a number of bootcomponents in sequence as follows.

Step 202 is for executing the first boot component.

Step 204 is for measuring an identifying characteristic of the next bootcomponent and storing the measurement in a register (for example 22.1).

Step 206 is for executing the next component.

Step 208 is for measuring an identifying characteristic of thesubsequent boot component, if any, and storing the measurement in asubsequent register (for example 22.2).

Step 210 represents a boot cycle repeating the steps of 206 and 208 forany subsequent boot components.

Step 212 is the end of the process when there are no more bootcomponents left.

In the preferred embodiment, a hypervisor performs initial steps (theequivalent steps 200, 202, 204 in the prior art) so that the measurementand execution starts in the hypervisor. For example, the hypervisorprovides a hypercall “H-Measure” which measures and executes some codelike a next boot component. In another example, platform firmware couldperform the initial steps and start a subsequent boot component in ahypervisor.

FIG. 3 is a simplified process diagram of prior art attestation process300 comprising a sequence of logical steps 302 to 308 as describedbelow. The attestation process executes after the trusted platform hasbooted.

Step 302 is for extracting measurements stored in registers.

Step 304 is for comparing the measurements with attestation values 34.1to 34N stored by the attestation system 30.

Step 306 is for indicating 1) a pass if the values match themeasurements or 2) a fail if there is a mismatch between the values andmeasurements.

Step 308 is the end of the process. The prior art attestation processtrusts that the attestation values are correct and in the prior art theattestation values are updated by an administrator.

FIG. 4 is a simplified process diagram of prior art update process 400comprising a sequence of steps 402 to 406.

Step 402 is for determining that a component needs to be updated with anewer version of the component.

Step 404 is for updating the component by removing the old component andloading the new component.

Step 406 is the end of the process. In this process there is noidentification that the component is a boot component and therefore noway of understanding that the update will have an impact of theattestation vale held by the attestation system.

FIG. 5 shows a comparison of results of the prior art trusted system andthe results of the trusted system of the preferred embodiment.

A complete prior art update and attestation comprises the followingcombined processes in sequence: 200, 300, 400, and 300 again. Bootprocess 200 loads the boot components and each component is measured inturn; the measurements are stored in TPM 20. Attestation process 300retrieves and tests the measurements against the stored attestationvalues and signals a pass because the values and measurements match.Update process 400 performs an update on one or more componentsincluding one or more boot components wherein the TPM measurement ischanged. A further execution of attestation process 300 indicates a failbecause there was no update to the attestation value and the attestationvalues and the TPM measurements do not match.

The preferred embodiment update and attestation process comprises thefollowing combined process steps in sequence: 606, 622, 700, and 622again. Boot process 606 loads the boot components; each boot componentis measured and the measurements are stored in a TPM. An embodimentattestation process 622 retrieves and tests the measurements against thestored attestation values and signals a pass because the values andmeasurements match. Embodiment update process 700 performs an update onone or more boot components and changes the measurements in the TPM. Inthe preferred embodiment the attestation system is notified that theupdate has been performed. Attestation process 622 indicates a passbecause it checks the origin of the update component.

In another embodiment the attestation values are updated withmeasurements established during the update.

FIG. 6 shows a schematic component diagram of the trusted computingsystem of the preferred embodiment. The trusted computing systemcomprises: platform 600; attestation system 620 and an update registry650.

Update registry 650 is a storage resource and index for holding thelatest versions of individual components of operating systems andapplications that are for use in updating instances of the operatingsystems or applications. In the figure, update registry comprisesupdates 651.1 to 650N. Scanning component version numbers or dates inthe update registry against component version numbers or dates of anoperating system instance reveals which components that need updating.

In operation, platform 600 is a hardware platform with a hypervisor 604for executing and managing virtual operating systems. An example of aplatform is an IBM Power System. In operation Hypervisor 604 comprises:boot process 606; update process 700; updaters 612.1 to 612N; and avirtual machine hosting environment. The hypervisor of the presentexample creates a single virtual machine 605 in the hosting environmentfor a single operating system 614 but the preferred embodimentanticipates that more than one operating system could be updated on morethan one virtual machine. Each virtual machine has a correspondingvirtual TPM. Each virtual machine executing on a hypervisor is trustedby the attesting system. The trust is gained by a real TPM or by currentand trusted signed updates and other security measures.

Virtual Trusted Platform Module 610 comprises a plurality of registers(PCRs) PCR1, 2, 3 . . . 17, 18 . . . N. Each PCR can store a measurementor value.

Updaters 612.1 to 612N comprise an example set of separate components,each associated with a respective boot component (616.1 to 616N) andeach can update the operating system with a respective update (651.1 to651N). For example, boot component 616.3 can be updated by updater 612.3using update 651.3 and so on for boot component 616N, updater 612N andupdate 651N. Each updater comprises links to corresponding updates andboot components. Each updater is intended to be measured and thenexecuted by the hypervisor. The measurement is stored in a first agreedregister (for example PCR17). During execution, an updater measures thenew component that it is installing and updates a second agreed register(for example PCR18). Note that the updater may just be copying somethingor, on the fly, creating the component. For example, updater “bosboot”generates a new operating system component image on the fly from manyconfiguration files and system data.

In a preferred embodiment the updater is adapted to notify the attestingsystem directly that the operating system has been updated. This mightmean that the updater making direct contact with the attestation systemor getting some common process on the hypervisor to make contact.Virtual OS System 614 (for example IBM AIX*), when loaded by thehypervisor, comprises boot components 616.1 to 616N that are loaded aspart of the boot process to provide a functioning virtual operatingsystem with applications, data and interfaces. Other operating systemcomponents that are not part of the boot process are not shown.

Boot process 606 comprises a process the same as prior art boot process200.

Attestation system 620 comprises: attestation process 622 andattestation values 624.1 to 624N. Attestation system 620 and hypervisor604 have an agreement over which registers (PCR1 . . . N) are used torecord the measurement of the updater and the signature of the changedcomponent (also called the identifying characteristic). In the preferredembodiment, these agreed registers are called first agreed register andsecond agreed register. For instance, in the example, the first andsecond agreed registers are PCR17 and PCR18.

The attestation system needs to attest the registers in the TPM. All theregister values will be transferred using an attestation protocol wheredigital signatures and other security mechanisms are used to keep thetrust. The attestation system can detect if the agreed registers (forexample first and second agreed registers PCR17 and 18) are set and isable to prepare for the reboot and subsequent change of the currentlytrusted registers (for example PCR1, 2 and 3).

The attestation system will read the first agreed register (for examplePCR17) and determine that the updater is a trusted updater. This isdetermined by: looking at a master list of measurements for known andtrusted updaters; and looking at a trusted boot event log that has beenupdated with meta-data for every change to the registers. When theattestation system finds that the first agreed register contains atrusted value then it assumes that second agreed register also containsa trust-worthy value to be used when next comparing the boot registerassociated with the updater detected in the update.

Referring to FIG. 7, hypervisor update process 700 comprises processlogic steps 702 to 710.

Step 702 is for determining that a boot component has an availableupdate by scanning the update registry 650 for more recent components.For instance, Virtual OS System 614 boot component 616.3 comprisesversion 1 of the AIX boot image (AIX Boot Image1) but update 651.3 inupdate registry 650 has been loaded with version 2 of the AIX boot image(AIX Boot Image2). This is preferred but in other embodiments adifferent mechanism may be used to determine when to update.

Step 704 is for loading the new boot component by activating theassociated updater (for example updater 612.3) and wherein theassociated updater is adapted to update the boot component; theassociated updater accesses the new boot component and installs the newboot component over or instead of the old boot component. The abovedescription is the essential operation of the boot loading step andfurther more detailed operation of the boot loading step is describedwith respect to FIG. 8 below.

Step 706 is for measuring a new boot component after it has been loadedinto the virtual operating system so that the new measurement uniquelyidentifies the new boot component in location in the virtual operatingsystem. The new measurement is added to a specific register in theTrusted Platform Module. In the preferred embodiment the attestationsystem 620 looks for and understands that the specific register holds anew measurement and not an old one.

Step 708 is for notifying the attestation system 620 that a bootcomponent has been updated.

Step 710 signals the end of update process 700.

Whilst step 704 of loading a new boot component is described above as asimple embodiment of the invention, the preferred embodiment of theinvention uses further processing to increase the level of confidence.Load new boot component process 704, as described below and referencingFIG. 8, is a preferred embodiment of the invention and comprises processsteps 802 to 812.

Step 802 is for identifying an update component associated with the bootcomponent. In the example below, a program called bosboot is invoked tore-write the AIX Boot Image1 with AIX Boot Image2.

Step 804 is for loading the identified updater into the operatingsystem.

Step 806 is for measuring the updater component and adding themeasurement to the first agreed register. In the example below, aprogram called Hypercall measures bosboot and extends the first agreedregister (for example PCR17) within the TPM.

Step 808 is for invoking the updater to install the update component. Inthe example below, Bosboot writes the new boot-image.

Step 810 is for measuring the new boot component and adding themeasurement to the second agreed register.

Step 812 is the end of the load new boot component process 704.

Referring to FIG. 9, there are described logical process steps 902 to910 of attestation process 622 according to the preferred embodiment.The attestation process executes after the trusted platform has bootedbut is independent of the trusted platform.

Step 902 is for extracting measurements stored in registers.

Step 904 is for comparing the measurements with attestation values 624.1to 624N stored by the attestation system 620.

Step 906 is for indicating a pass if the values match the measurements.

Step 908 is for indicating a pass if any non-matching boot measurementsfrom step 906 match a known updater.

Step 910 is for indicating a fail if there are non-matching bootmeasurement after steps 908 and 910.

Step 912 is for indicating the end of the process.

EXAMPLE

An example of the operation of the preferred embodiment comprises an IBMPower* system hosting an IBM Power Hypervisor (PHYP) with a singlevirtual AIX system. The AIX system uses a virtual TPM device andincorporates trusted boot functionality. The system is monitored andattested by a separate attestation system. When attested the followingPCR measurements are returned where PCR1, PCR2, PCR3 are registers inthe TPM.

PCR1=Open-Firmware PCR2=AIX Boot-Image PCR3=AIX Trusted ExecutionDatabase

The attestation system considers these measurements to be trusted andwill not flag a security issue when they are returned via attestation.In order to allow the AIX boot-image to be modified and for theattestation system to be informed of this update the following featuresalso exist.

PHYP is modified so that it has a new method (referred to as a hypercalland specifically H_Measure). H_Measure takes parameters describingsomething to be measured and executed, for example, address and length.The resulting measurement is placed in a particular register of the TPM,for example, PCR17. The particular boot register is not important butcan be an absolute addressed register or an indirectly addressedregister. The importance is that the attestation system understandswhere to look. PHYP returns control to AIX at the address passed, thecritical difference is that the hyper-call is used firstly to measure acomponent and then secondly to execute the same component. What ismeasured is then executed.

In order to work, the hypervisor too must be trusted. In the prior arthypervisor trust is gained by the IBM Power System having a veryrestrictive way of updating the PHYP code and only IBM Power Systemsigned updates can be installed. In the present embodiment the IBM POWERSystem has a real TPM device and that PHYP is measured into thereal-TPM. A technique known as deep-attestation can be used to retrievethe real TPM measurements via the virtual AIX system.

A defined set of AIX programs, referred to as updaters in thespecification, are allowed to change components of the trusted boot. Inthis example, bosboot is defined as being the only updater program thatcan legally update the AIX boot-image. The technique requires thatbosboot can be trusted and therefore when bosboot is built, a digitalsignature of bosboot is taken and publicised. In order for H_Measure tobe able to measure bosboot successfully, bosboot should be a singlestatic piece of code that can be loaded into a contiguous piece ofmemory for the measurement to take place. It is important that bosbootis measureable. Bosboot does not have to be static if other securitymeasures are in place to ensure that non-static programs can't besubverted easily.

In this example AIX Boot-Image1 will be changed to AIX Boot-Image2informing the attestation system such that an unnecessary securityviolation is prevented. The operations are as follows:

1. bosboot (an updater) is invoked (step 702) to re-write theboot-image.2. The AIX kernel loads (step 704) bosboot into memory and callsH_Measure.3. PHYP measures (step 706) bosboot and extends PCR17 within the TPM.4. Execution is passed to bosboot by the hypervisor and bosboot writesthe new boot-image and extends PCR18 with a measurement of AIXBoot-Image2. Again just like PCR17, it is not important which registeris used, as long as the attesting system knows that PCR18 has a specialmeaning.5. The attestation system is informed (step 708) that it shouldre-attest, no more information need be exchanged.

Now when the attestation system attests the system the following valuesare returned (step 902).

PCR1=Open Firmware PCR2=AIX Boot-Image1 PCR3=AIX Trusted-ExecutionDatabase′

PCR17=bosboot

PCR18=AIX Boot-Image2

The attestation system will see that PCR17 has changed since the lastattestation, this triggers an action (step 908) in the attestationsystem. Firstly the value of PCR17 is checked, it sees that a legal, IBMpublished bosboot was invoked, therefore it knows that PCR18 will be anew AIX boot-image. Now when the attested system completes a new trustedboot, the attestation system can see that the new value reported viaPCR1 came from a trusted bosboot and no action is required.

EMBODIMENTS

The preferred embodiment, using a hypervisor to manage a virtual machineoperating environment, is described above including other embodimentswhere a single feature may depart from the preferred embodiment in someway.

An embodiment that departs from the preferred embodiment in a major wayconsiders an embodiment with no virtualization, a non-virtual embodimentas shown in FIG. 10. This embodiment comprises: platform 1000;attestation system 1020 and an update registry 1050. Platform 1000designed and manufactured in silicon. Like the preferred embodiment TPM1010 is not an essential part and some other secure device/storage couldbe used that holds measurements and something like attestation.

Update registry 1050 is a storage resource and index for holding thelatest versions of individual components of operating systems andapplications that are for use in updating instances of the operatingsystems or applications. In the figure, update registry comprisesupdates 1051.1 to 1050N. Scanning component version numbers or dates inthe update registry against component version numbers or dates of anoperating system instance reveals which components that need updating.

Attestation system 1020 comprises attestation process 1022 andattestation values 1024.1 1024N. Apart from the difference that theoperating system is a real operating system running on a physicalmachine the attestation process 1022 and attestation values 1024.1 . . .1024N are the similar to those shown in FIG. 6.

In operation, platform 1000 is a hardware platform comprises: bootprocess 1006; update process 1700; updaters 1012.1 to 1012N; TPM 1010;and operating system 1014. Like the preferred embodiment TPM 1010 is notan essential part and some other secure device/storage could be usedthat holds measurements and something like attestation.

In the non-virtual embodiment, a TPM 1010 comprises special registers(SR1 . . . SRN) which can be used to hold measurements. SRs behave justlike PCRs in that a write to them is really a write of a new valuecombined with the old value and then hashed using a strong hashalgorithm. The processor has instructions which allow these specialregisters (SRs) to be updated. The processor is modified to have aMeasure instruction. This instruction takes an identifier for an SR,memory address and a length. It measures the data at the address (andall bytes up to length) then stores the measurement in the specified SR.The processor transfers execution to the address.

In the non-virtual embodiment, platform 1000 will need to update somecode and there is update code associated with the some code forperforming the update. The associated code is loaded into memory thenthe Measure instruction is used to measure and execute the associatedcode. The measurement is placed in a first agreed register. The executedassociated code can now install the some code, this is probably justwriting data to disk. Before the write, or before each write (if thereis some write n-bytes limitation) measurements are taken and writteninto a second agreed register (an SR and this correlates to the updateof the second agreed register PCR18).

In the non-virtual embodiment, platform 1000 must inform an attestingsystem 1020 that an update has occurred. As with the preferredembodiment attestation system 1020 attests, this transfers the values ofthe SRs using cryptographic techniques to maintain trust. Attestationprocess 1022 is similar to the preferred embodiment.

It will be clear to one of ordinary skill in the art that all or part ofthe method of the described embodiments of the present invention maysuitably and usefully be embodied in a logic apparatus, or a pluralityof logic apparatus, comprising logic elements arranged to perform thesteps of the method and that such logic elements may comprise hardwarecomponents, firmware components or a combination thereof.

It will be equally clear to one of skill in the art that all or part ofa logic arrangement according to the described embodiments of thepresent invention may suitably be embodied in a logic apparatuscomprising logic elements to perform the steps of the method, and thatsuch logic elements may comprise components such as logic gates in, forexample a programmable logic array or application-specific integratedcircuit. Such a logic arrangement may further be embodied in enablingelements for temporarily or permanently establishing logic structures insuch an array or circuit using, for example, a virtual hardwaredescriptor language, which may be stored and transmitted using fixed ortransmittable carrier media.

It will be appreciated that the method and arrangement described abovemay also suitably be carried out fully or partially in software runningon one or more processors (not shown in the figures), and that thesoftware may be provided in the form of one or more computer programelements carried on any suitable data-carrier (also not shown in thefigures) such as a magnetic or optical disk or the like. Channels forthe transmission of data may likewise comprise storage media of alldescriptions as well as signal-carrying media, such as wired or wirelesssignal-carrying media.

The present invention may further suitably be embodied as a computerprogram product for use with a computer system. Such an implementationmay comprise a series of computer-readable instructions either fixed ona tangible medium, such as a computer readable medium, for example,diskette, CD-ROM, ROM, or hard disk, or transmittable to a computersystem, using a modem or other interface device, over either a tangiblemedium, including but not limited to optical or analogue communicationslines, or intangibly using wireless techniques, including but notlimited to microwave, infrared or other transmission techniques. Theseries of computer readable instructions embodies all or part of thefunctionality previously described herein.

Those skilled in the art will appreciate that such computer readableinstructions can be written in a number of programming languages for usewith many computer architectures or operating systems. Further, suchinstructions may be stored using any memory technology, present orfuture, including but not limited to, semiconductor, magnetic, oroptical, or transmitted using any communications technology, present orfuture, including but not limited to optical, infrared, or microwave. Itis contemplated that such a computer program product may be distributedas a removable medium with accompanying printed or electronicdocumentation, for example, shrink-wrapped software, pre-loaded with acomputer system, for example, on a system ROM or fixed disk, ordistributed from a server or electronic bulletin board over a network,for example, the Internet or World Wide Web.

In an alternative, the preferred embodiment of the present invention maybe realized in the form of a computer implemented method of deploying aservice comprising steps of deploying computer program code operable to,when deployed into a computer infrastructure and executed thereon, causethe computer system to perform all the steps of the method.

In a further alternative, the described embodiments of the presentinvention may be realized in the form of a data carrier havingfunctional data thereon, said functional data comprising functionalcomputer data structures to, when loaded into a computer system andoperated upon thereby, enable said computer system to perform all thesteps of the method.

It will be clear to one skilled in the art that many improvements andmodifications can be made to the foregoing exemplary embodiment withoutdeparting from the scope of the present invention.

SUMMARY OF PREFERRED EMBODIMENT

In summary this invention relates to a method and apparatus for updatingan operating system executing in a trusted computing hypervisorenvironment. In particular this invention relates to a method, systemand computer program for updating an operating system executing in ahypervisor environment comprising: determining a new version of acomponent of an operating system; installing the new component version;measuring an identifying characteristic of the component and making itavailable to an attestation system; notifying the attestation systemthat a component has been updated to a new version whereby, when theattestation system finds that the identifying characteristic of the newcomponent does not match a pre-stored attestation value it is aware thata legitimate mis-match could have occurred. The installing of the newversion of the component comprises: identifying an updater associatedwith new version of the component; measuring an identifyingcharacteristic of the identified updater; loading and installing the newversion of the component; and making both the identifying measurement ofthe updater and the new version of the component available to theattestation system.

NOTICES

*IBM, AIX, Express, ibm.com, Power, Power7 and Tivoli are trademarks orregistered trademarks of International Business Machines Corporation inthe United States, other countries or both. A full list of U.S.trademarks owned by IBM may be found at:www.ibm.com/legal/copytrade.shtml.

1. A method for updating and attesting code in a execution environmentcomprising: installing new code; measuring an identifying characteristicof the new code and making it available to an attestation system;notifying the attestation system that code has been updated to a newversion whereby; and whereby when the attestation system finds that theidentifying characteristic of the new code does not match a pre-storedattestation value it is aware that a legitimate mis-match could haveoccurred.
 2. A system for updating and attesting code in a executionenvironment comprising: installation means for installing new code;measuring means for measuring an identifying characteristic of the newcode and making it available to an attestation system; notifying meansfor notifying the attestation system that code has been updated to a newversion whereby; and whereby when the attestation system finds that theidentifying characteristic of the new code does not match a pre-storedattestation value it is aware that a legitimate mis-match could haveoccurred.
 3. A system of testing the integrity of a program comprising:extracting a code measurement stored by the program installationprocess; testing means for testing the code measurement with referencemeasurements stored by the testing system and failing the measurement ifit does not match; further testing means for testing the failed codemeasurement and failing it again if the measurement does not originatefrom a component known to the testing system; and indicating means forindicating a pass if the code measurement passes a test and a fail ifone code measurement does not pass either of the tests.
 4. A computerprogram product for creating a first computer resource at a clientcomputer, the computer program product comprising: a computer readablestorage medium readable by a processing circuit and storing instructionsfor execution by the processing circuit for performing a methodaccording to claim
 1. 5. A computer program stored on a computerreadable medium and loadable into the internal memory of a digitalcomputer, comprising software code portions, when said program is run ona computer, for performing the method of claim 1.